Natural selection describes the process where variations in traits differentially affect survival and reproductive success between individuals in natural settings.
For natural selection to occur, phenotypes in a population must be variable, heritable, and result in variation in fitness of organisms.
Populations of a species contain genetic variations that are passed down among generations. These differences allow certain individuals to fare better in survival and/or reproduction.
By adapting the concept of natural selection, humans have created a variety of domesticated plants and animals by selecting favorable traits.
Many of the crops and domesticated animals we keep today are an outcome of artificial selection. Artificial selection has enabled us to produce crops and animals more efficiently.